This application relates to estimating location and tracking of passive or active sensors and in particular is related to using phased array antenna systems and Radio Frequency Identification (RFID) system to locate sensors and/or RFID tags.
An RFID system conventionally includes a set of stationary or mobile RFID tags typically manipulated by a reader/interrogator system. Each sensor may be passive or active, i.e., with or without a battery. In conventional systems, the reader and the RFID tags are generally required to be in close proximity so that the tags can operate in close proximity to the reader antenna.
The limited transmission distances available with conventional. RFID systems limit their use in an automated factory setting and/or in an indoor wireless environment. Even within the designed range of operation, such systems often have low reliability due to interferences and collisions.
Typical RFID systems also are not designed to cover extremely large areas as multiple base stations are needed to provide sufficient coverage for the area. This can be extremely expensive and thus cost prohibitive. Also, sacrifices are made to compensate for the large area by limiting the coverage area to select high use regions, e.g., at dock doors. Additionally, such systems often do not provide precise location determinations of the RFID due to the complexity in the size and space of the environment. Accordingly, there is a need for a RFID system that overcomes the above-noted obstacles and the shorting comings in the art.